Preliminary Research into selected cities:

Tokyo, 33.6 million

Mexico City, 22.4 million

New York City, 21.9 million

Mumbai, 21.6 million

Sao Paulo, 20.6 million

Los Angeles, 18 million

Shanghai, 17.5 million

Cairo, 16.1 million

Kolkata, 15.7 million

Jakarta, 15.1 million

Karachi, 15.1 million

Buenos Aires, 13.6 million

Moscow, 13.5 million

Beijing, 12.8 million

Tehran, 12.1 million

London, 12 million

Istanbul, 11.8 million

Lagos, 10.1 million